1. Field
Example embodiments relate to an image sensor using a light-sensitive device and a method of operating the image sensor, and more particularly, to an image sensor using a light-sensitive oxide semiconductor material as a light-sensitive device and a method of operating the image sensor for acquiring RGB values of incident light in the image sensor.
2. Description of the Related Art
Image sensors are used in various fields (e.g., high-density image sensors may be used in high definition cameras, ultraviolet/infrared ray sensitive image sensors may be used in touch panels, etc.). The most popular examples of currently commercialized image sensors include charge coupled sensor (CCD) image sensors and complementary metal oxide semiconductor (CMOS) image sensors, for example. Such CCD sensors and CMOS sensors include PN junctions of a semiconductor (e.g., silicon) as the basic structures.
Currently, CCD image sensors are widely commercialized. However, CCD image sensors have complicated driving mechanisms, intensive power consumption and/or complicated fabrication processes. CMOS image sensors are being considered as the next-generation of image sensors.
A CMOS image sensor is a solid imaging device using a CMOS. Although a CMOS image sensor also uses a photo diode (similar to a CCD image sensor), fabrication processes and methods of reading signals differ for a CCD image sensor. Generally, each unit pixel of a CMOS image sensor includes a photo diode and a transistor. Therefore, an image may be embodied by sequentially detecting electric signals of each of the unit pixels by using a simple switching method. Because such a CMOS image sensor may be mass-produced by using a general semiconductor fabrication device, a CMOS image sensor features lower fabrication costs, smaller size and/or less power consumption, as compared to a CCD image sensor.
A CMOS sensor may be fabricated as a single chip together with various signal processing devices. Because an amplifier is allocated to each pixel in the conventional CMOS image sensors, the conventional CMOS image sensors exhibit noise due to differences in amplifier characteristics. However, by making various enhancements, a signal-noise ratio is significantly improved.
Recently, technical competition for improving the integration of an image sensor by applying finer processes to image sensor fabrication has increased. A larger number of image sensors with the same number of pixels may be fabricated per wafer by reducing a chip size and by applying a fine semiconductor process. As a result, costs of an image sensor may be reduced, productivity of the image sensor may be increased, and a size of a camera module may be reduced. Therefore, the reduction of a chip size and application of a fine semiconductor process may be used, for example, to manufacture a smaller camera phone. Currently, a technique for forming a unit pixel having a size of 1.4 μm may be performed, and approximately 12.25 million pixels may be embodied with an image sensor having a size of 1.25 inches.